OVP help,, simple question - Page 2 - PeachParts Mercedes-Benz Forum

cliffmac · #1 09-02-2009, 08:58 PM

on the 89 you will get a 'Check Engine' light...if not, it's something else...

cliffmac · #2 09-02-2009, 09:00 PM

this OVP is very overrated...really...

tinypanzer · #3 09-02-2009, 09:08 PM

Quote:

Originally Posted by cliffmac

this OVP is very overrated...really...

Maybe, but it still bit me in the ass twice on the same car.....

Cal Learner · #4 09-03-2009, 06:47 AM

Quote:

Originally Posted by ps2cho

If the ABS light is on and your ABS is functional -- It's the OVP...

Is this so? Since the OVP is the power source for the ABS controller, if the OVP is bad and the ABS light is on, it's because the ABS controller (and, therefore, the ABS system) is inop. Isn't that so?

Quote:

Originally Posted by ps2cho

...I've never heard of the light come on for any other reason...

My ABS light was on because of a bad speed sensor on one of the front wheels. In my case, the OVP was fine.

babymog · #5 09-02-2009, 09:19 PM

I've replaced three in the past 2years (different cars), it cured the symptoms each time.

Very common failure, there's even an engineering change to the original relay (different part number).

Cal Learner · #6 09-09-2009, 07:45 AM

Allen, this should get you going. The first page is the testing proc and the second is the resistance-temperature scale to compare your results to for specification at several temps.

dlevitt · #7 09-12-2009, 07:16 PM

With the 4 pin style temp sensor, I believe that the resistance is measured across opposite pins [e.g. 12 o'clock and 6 o'clock]

My M103 has a two connectors, matching the Bosch unit in the online catalog described as

Quote:

M103.983 - A/T up to 181461 Fed; At cylinder head; C.I.S.;Green; 2 pins; Bosch # 0 280 130 044;Packing Size

IECE;

[interesting how vBulletin added the smily in the quote - maybe it's trying to tell me something]

Does this sensor just have one circuit [measure from pin to pin] or two circuits [measure from each pin to ground]?

Time to go to the store an get a better meter anyway [next steps are to look at the 'duty cycle' readings and the output voltage from the O2 sensor - can't do either with my cheapie meter]

Cal Learner · #8 09-13-2009, 07:17 AM

Quote:

Originally Posted by dlevitt

With the 4 pin style temp sensor, I believe that the resistance is measured across opposite pins [e.g. 12 o'clock and 6 o'clock] Does this sensor just have one circuit [measure from pin to pin] or two circuits [measure from each pin to ground]?

If you're talking about your '89 300E, the sensor is actually two identical sensors in the same component. One sensor supplies signal to the KE controller for fuel management, and the other supplies signal to the EZL for ignition management. The 4 pins are indeed measured on the diagonal, pins 1 and 3, then pins 2 and 4. Pins 3 and 4 are ground. The measured resistance for each pair of tests should be identical at the same temperature point shown in the chart above.

dlevitt · #9 09-13-2009, 02:32 PM

My 89 300E has a two pin connector [two circular posts, with o-rings on each one]

Image from the catalog [if this works]

Measuring from each post to ground shows about 2 ohms [cheapie analog meter] at current ambient temp [80F] - that should be closer to 1.7k ohms. If I'm reading things correctly it's time to order a new sensor.

wrnmnro · #10 09-02-2009, 11:34 PM

My 89 300sel has had the engine light on for awhile. The other day, after reading about code( mine was 4)...I pulled it off its mount, tried to unplug it(did not want to break) moved it around and checked fuse. Replaced it and the engine light went off!!! For 2 days no problem...ran great, but I turned on a/c which does not work just to put a load on and bam the light came back on. Went thru the same exercise and light went off again.

Any ideas, suggestions as to why. I do have issues with a/c...heater is always on it seems......
Thanks and the lil box is important!!!!!!!!!!!!1

allenbistany · #11 09-05-2009, 10:28 PM

Alright guys i swapped the Ovp from the 91 300e to my 89 300e and still broken. I then took the ovp and started the car and it took longer to start and the ABS light was on and ran even more rougher than right now. So OVP is out of the question whats next?

Cal Learner · #12 09-06-2009, 07:03 AM

Allen, you don't say what maintenance history is or what else has recently been done to the car since your symptoms first appeared. It's time to haul out the multimeter and the CIS fuel pressure tester and start systematic diagnostic testing of the ignition/electrical and fuel systems. The tests themselves are surprisingly easy and quick to perform. That will begin to narrow down the list of possible causes. Then post back any results that are questionable and you'll no doubt get knowledgeable help.

whunter · #13 09-06-2009, 03:06 PM

OVP relay, Over Voltage Protection Links
OVP relay, Over Voltage Protection Links

Code data..

Jim Forgione's DIY articles
http://www.k6jrf.com/MB_S500.html

Have a great day.

allenbistany · #14 09-06-2009, 05:30 PM

The car had all the necessary tune ups 1 or 2 years ago, plugs wires distributor cap/rotor, full tune up. Heres the story. The problem where i press the gas and go no where (flat spots) happened awhile back. So i brought my car to my mechanic and we put a gas analyzer in the exhaust. The car was running as rich as possible. So buy turning the screw over the intake manifold we brought down the Ho, Co2, then i drove around for about a week and was noticing that when i stoped at a light the whole car started shaking and rpms droped, vacuum was at the middle/red like it does now but when the car reached optimal temperature it stopped doing it, , . So i brought it back to the mechanics and his solution was to up the richness of the fuel basically to mask the problem. It worked though for about a year all of a sudden it happened again in like June of this year but now it happens all the time even at optimal temperature. So im kind of hoping for something to break or coming up with a real solution. I dont have the necessary tools to diagnose the car..

babymog · #15 09-07-2009, 01:17 PM

Have you checked: Temperature sensor, fuel pressure (filters and pump operation).

The temperature sensor enables cold enrichment and if reading cold, could cause the car to run rich.

The fuel pressure is an important part of the fuel mix also: When fuel pressure is low in a CIS system, the counter-pressure on the metering pin will be low and allow the air-flow sensor plate to rise too far, injecting too much fuel. If the fuel pressure is lower still, the car will not run well due to inadequate fuel flow and pattern. Fuel filters can be a culprit here and are a good place to start if they haven't been serviced.